As I recall, average have jobs. Jobs are becoming PC oriented all the time. That is because the PC architecture (screen, local storage, keyboard) is pretty much needed for full-time production on a PC (and when has been computerized that means that less, not more, physical activity will be needed).
Post-PC products may indeed continue making inroad in consumption and those jobs where people need to walk-around. But outside that, the form factor that is the tablet's advantage become its disadvantage and only obsessive cool-aid swallows will take it beyond these areas.